Police say 65-year-old Daniel Donatto was last seen around 4 p.m. Saturday in the 4700 block of Lexington Boulevard.
According to his family, Donatto wandered off from his nursing home.
Officers say he has been diagnosed with a cognitive impairment.
Donatto is described as a Black man, 5'8", 160 pounds, with gray hair, last seen wearing a black hat, blue jacket, gray pants and black and white shoes.
Officials believe Donatto's disappearance poses a credible threat to his own health and safety.
If you've seen him, you're urged to call Missouri City Police at (281) 403- 8700